The effects of the geometric and optical parameters on the performance of a grating perfect absorber sensor in near-infrared band

We use in this work a gold grating structure, as a plasmonic refractive index sensor, for sensing chemical or biological entities in aqueous solutions. This device was operated in an infrared band by using the rigorous coupled-wave analysis. The performance parameters of the proposed sensor in terms of absorbance at resonance are refractive index sensitivity, figure of merit (FoM), and quality factor (QF), were examined by applying the optical interrogation technique. Based on some numerical results, we optimize the geometric structure and the direction of the incident light to improve the performance of our device as a perfect absorber sensor. The analysis of the results obtained shows us the effect of several geometric and also optical parameters on the function of the instrument proposed as an optical detector of the variation of the refractive index. Our detector shows excellent results compared to others published in the literature. With azimuthally incident direction and optimal geometric and optical parameters, we obtain an optimal absorbance peak ranging between 99.92 and 99.99%, a high refractive index sensitivity of 1400 nm/RIU, a FoM of 211.54 RIU −1 , and a QF of 285.28. In addition, the performance of our sensor is demonstrated by high sensitivity values of 1555.55 nm/RIU and 1522.84 nm/RIU for polydimethylsiloxane and ethanol solutions.